C#

George_George wrote:

For String.Empty, as you said, it represents a string initialized, but length is zero. Initialized means constructed (constructor called)?

string

Rutvik Dave wrote:

If All the variables initialized to

String.Empty

Then They will point to different memory address

Rutvik Dave wrote:

It is not possible that you create two different reference type variables and they have same memory reference, unless you assign one variable to another.

Rutvik Dave wrote:

remeber that string is immutable. so every time you change the value it will be allocated and initialize with the new value again

Colin Angus Mackay wrote:

Rutvik Dave wrote:
It is not possible that you create two different reference type variables and they have same memory reference, unless you assign one variable to another.

That is correct, but it does not apply to the current situation as you are not creating different objects. You are referencing an existing object.

string str1 = "hello world";
string str2 = "hello world";
if (str1 == str2) Console.WriteLine("same reference");

leppie wrote:

Erm, == is overriden for string

Two string values are considered equal when one of the following is true:

    * Both values are null.
    * Both values are non-null references to string instances that have identical lengths and identical characters in each character position.

Colin Angus Mackay wrote:

Incorrect. Here is what reflector has to say on the subject:
public static readonly string Empty;

That means there is only one representation ever in memory. It is not copied, it is referenced. That means they will ALL point to the same memory address.

((object)"") == String.Empty :::: False
("") == String.Empty         :::: True

((object)"") == String.Empty :::: True
("") == String.Empty         :::: True

George_George wrote:

What do you mean "It is not copied, it is referenced"? Could you show some pseude code please?

George_George wrote:

"create two different reference type variables and they have same memory reference"

George_George wrote:

you create a base type variable (reference type) and a derived type variable (reference type), they are of different types but pointing to the same memory address

George_George wrote:

I am doing input parameter checking for a string type, and string value except empty is valid. My function is provided to outer client to call. Sometimes I find to check null is not enough, I also need to check String.Empty.